Toward Enhanced Oxygen Evolution on Perovskite Oxides Synthesized from Different Approaches: A Case Study of Ba0.5Sr0.5Co0.8Fe0.2O3−δ

•BSCF was prepared by solution combustion, sol-gel process and solid-state reaction.•Solid-state reaction synthesized BSCF-SS has the highest OER activity.•The OER activity variation is due to the difference in oxidation states of Co ions.

Development of electrocatalysts for the oxygen evolution reaction (OER) plays a critical role in electrochemical water splitting systems. Perovskite oxides represent one category of efficient catalysts for the OER, among which Ba0.5Sr0.5Co0.8Fe0.2O3−δ (BSCF) has been extensively studied. In this work, we discussed the effect of synthesis approaches on the OER performance of BSCF. Three routes, including solution combustion, sol-gel process and solid-state reaction, were applied to synthesize the bulk-sized BSCF perovskites, denoted as BSCF-SC, BSCF-SG and BSCF-SS, respectively. Electrochemical measurements revealed varied OER performance, with BSCF-SS showing the highest intrinsic activity much better than that of BSCF-SC and BSCF-SG. The activity difference may originate from the variation in the surface oxidation states of the B-site cobalt cations. Moreover, all the BSCF perovskites exhibited comparably good stability in catalyzing the OER. In light of the simplicity, the viability for scale-up and the high activity of BSCF-SS, solid-state reaction may be a suitable way for fabricating highly-active BSCF electrocatalyst. This study could provide new insight into enhanced oxygen evolution on perovskite oxides by selecting an optimized synthesis approach.

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